(i) Technical Field
The present invention relates to an optical semiconductor device having two waveguides having different widths.
(ii) Related Art
There is known a modulator-integrated type semiconductor laser as an optical semiconductor device having two waveguides (see, for example, Japanese Patent Application Publication No. 2003-298175). The proposed modulator-integrated type semiconductor laser has a single semiconductor substrate on which a semiconductor laser and an optical modulator are mounted.